Polymeric delivery formulations of leuprolide with improved efficacy

ABSTRACT

The present invention is directed to a flowable composition that is suitable for use as a controlled release implant. The flowable composition includes a biodegradable thermoplastic polyester that is at least substantially insoluble in aqueous medium or body fluid. The flowable composition also includes a biocompatible polar aprotic solvent. The biocompatible polar aprotic solvent is miscible to dispersible in aqueous medium or body fluid. The flowable composition also includes leuprolide acetate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/872,671, filed Jun. 21, 2004, which is a continuation of U.S. patentapplication Ser. No. 10/373,400, filed Feb. 24, 2003 which is acontinuation of U.S. application Ser. No. 09/711,758, filed Nov. 13,2000 and issued as U.S. Pat. No. 6,565,874, which is acontinuation-in-part of U.S. patent application Ser. No. 09/666,174,filed on Sep. 21, 2000 and a continuation-in-part of U.S. patentapplication Ser. No. 09/643,289, filed Aug. 22, 2000 and issued as U.S.Pat. No. 6,630,155, which in turn is a continuation application of U.S.patent application Ser. No. 09/181,355, filed Oct. 28, 1998 and issuedas U.S. Pat. No. 6,143,314, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Leuprolide acetate is an LHRH agonist analog that is useful in thepalliative treatment of hormonal related prostate cancer, mammarycancer, endometriosis, and precocious puberty. With continued use,leoprolide acetate causes pituitary desnsitizing and down-regulation toaffect the pituitary-gonodal axis, leading to suppressed circulatinglevels of luteinizing and sex hormones. In patients with advancedprostate cancer, achieving circulating testosterone levels of less thanor equal to 0.5 ng/ml (chemical castration level) is a desiredpharmacological indicator of therapeutic action.

Originally, leuprolide acetate was launched in the United States as adaily subcutaneous (s.c.) injection of the analog solution. Theinconvenience of chronic repetitive injections was later eliminated bythe development of a one month sustained release depot product based onpoly(DL-lactide-co-glycolide) microspheres (Lupron® Depot). Currently,one, three, and four month formulations are widely available asintramuscular (i.m.) injections of microspheres.

Although the current Lupron® Depot microspheres appear to be effective,the microsphere products are difficult to manufacture, and they allrequire a deep intramuscular (i.m.) injection using large volumes offluid to ensure that all of the microspheres are properly administeredto the patient. These injections are often painful and lead to tissuedamage.

Biodegradable polymers other than Lupron® Depot have been employed inmany medical applications, including drug delivery devices. The drug isgenerally incorporated into the polymeric composition and formed intothe desired shape outside the body. This solid implant is then typicallyinserted into the body of a human, animal, bird, and the like through anincision. Alternatively, small discrete particles composed of thesepolymers can be injected into the body by a syringe. Preferably,however, certain of these polymers can be injected via syringe as aliquid polymeric composition.

Liquid polymeric compositions useful for biodegradable controlledrelease drug delivery systems are described, e.g., in U.S. Pat. Nos.4,938,763; 5,702,716; 5,744,153; 5,990,194; and 5,324,519. Thesecompositions are administered to the body in a liquid state or,alternatively, as a solution, typically via syringe. Once in the body,the composition coagulates into a solid. One type of polymericcomposition includes a nonreactive thermoplastic polymer or copolymerdissolved in a body fluid-dispersible solvent. This polymeric solutionis placed into the body where the polymer congeals or precipitativelysolidifies upon the dissipation or diffusion of the solvent into thesurrounding body tissues. It is expected that these compositions wouldbe as effective as Lupron® Depot, since leuprolide of these compositionsis the same as are in the Lupron® Depot and the polymers are similar.

Surprisingly, however, it has been discovered that the liquid polymericcompositions according to the present invention are more effective indelivering leuprolide acetate than Lupron® Depot. Specifically, thetestosterone levels obtained with the liquid polymeric compositions ofthe present invention containing the leuprolide acetate are lower atextended times in dogs compared to Lupron® Depot, and also at the sixmonth point in humans, compared to the value reported in the literaturefor Lupron® Depot (Sharifi, R., J. Urology, Vol. 143, January, 68(1990)).

SUMMARY OF THE INVENTION

The present invention provides a flowable composition that is suitablefor use as a controlled release implant of leuprolide acetate. Theflowable composition includes a biodegradable thermoplastic polyesterthat is at least substantially insoluble in an aqueous medium or bodyfluid. The flowable composition also includes a biocompatible polaraprotic solvent. The biocompatible polar aprotic solvent can be anamide, an ester, a carbonate, a ketone, an ether, or a sulfonyl. Thebiocompatible polar aprotic solvent is miscible to dispersible inaqueous medium or body fluid. The flowable composition also includesleuprolide acetate. The leuprolide acetate is preferably present inabout 2 wt. % to about 4 wt. % of the composition or in about 4 wt. % toabout 8 wt. % of the composition. Preferably, the flowable compositionis formulated as an injectable subcutaneous delivery system. Theinjectable composition preferably has a volume of about 0.20 mL to about0.40 mL or about 0.30 mL to about 0.50 mL. The injectable composition ispreferably formulated for administration about once per month, aboutonce per three months, or about once per four months to about once persix months. Preferably, the flowable composition is a liquid or a gelcomposition, suitable for injection into a patient.

Preferably, the biodegradable thermoplastic polyester is a polylactide,a polyglycolide, a polycaprolactone, a copolymer thereof, a terpolymerthereof, or any combination thereof. More preferably, the biodegradablethermoplastic polyester is a polylactide, a polyglycolide, a copolymerthereof, a terpolymer thereof, or a combination thereof. Morepreferably, the suitable biodegradable thermoplastic polyester is 50/50poly (DL-lactide-co-glycolide) having a carboxy terminal group or is75/25 poly (DL-lactide-co-glycolide) with a carboxy terminal group thatis protected. The suitable biodegradable thermoplastic polyester can bepresent in any suitable amount, provided the biodegradable thermoplasticpolyester is at least substantially insoluble in aqueous medium or bodyfluid. The suitable biodegradable thermoplastic polyester is preferablypresent in about 30 wt. % to about 40 wt. % of the flowable compositionor is present in about 40 wt. % to about 50 wt. % of the flowablecomposition. Preferably, the biodegradable thermoplastic polyester hasan average molecular weight of about 23,000 to about 45,000 or about15,000 to about 24,000.

Preferably, the biocompatible polar aprotic solvent isN-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, dimethylsulfoxide, propylene carbonate, caprolactam, triacetin, or anycombination thereof. More preferably, the biocompatible polar aproticsolvent is N-methyl-2-pyrrolidone. Preferably, the polar aprotic solventis present in about 60 wt. % to about 70 wt. % of the composition or ispresent in about 45 wt. % to about 55 wt. % of the composition.

The present invention also provides for a method for forming a flowablecomposition. The flowable composition is useful as a controlled releaseimplant. The method includes mixing, in any order, a biodegradablethermoplastic polyester, a biocompatible polar aprotic solvent, andleuprolide acetate. These ingredients, their properties, and preferredamounts are as disclosed above. The mixing is performed for a sufficientperiod of time effective to form the flowable composition for use as acontrolled release implant. Preferably, the biocompatible thermoplasticpolyester and the biocompatible polar aprotic solvent are mixed togetherto form a mixture and the mixture is then combined with the leuprolideacetate to form the flowable composition.

The present invention also provides for a biodegradable implant formedin situ, in a patient. The biodegradable implant product is prepared bythe process of injecting a flowable composition within the body of thepatient and allowing the biocompatible polar aprotic solvent todissipate to produce a solid biodegradable implant. These ingredients,their properties, and preferred amounts are as disclosed above.Preferably, the patient is a human. The solid implant preferablyreleases the effective amount of leuprolide as the solid implantbiodegrades in the patient.

The present invention also provides for a method of forming abiodegradable implant in situ, in a living patient. The method includesinjecting the flowable composition of the present invention within thebody of a patient and allowing the biocompatible polar aprotic solventto dissipate to produce a solid biodegradable implant. The flowablecomposition includes an effective amount of a biodegradablethermoplastic polyester, an effective amount of a biocompatible polaraprotic solvent, and an effective amount of leuprolide acetate. Theseingredients, their properties, and preferred amounts are as disclosedabove. Preferably, the solid biodegradable implant releases theeffective amount of leuprolide acetate by diffusion, erosion, or acombination of diffusion and erosion as the solid implant biodegrades inthe patient.

The present invention also provides a method of treating or preventingcancer in a patient. The method includes administering to the patient inneed of such treatment or prevention an effective amount of a flowablecomposition of the present invention. Specifically, the cancer can beprostate cancer. In addition, the patient can be a human.

The present invention also provides a method of reducing LH levels in apatient. The method includes administering to the patient in need ofsuch LH reduction an effective amount of a flowable composition of thepresent invention. Specifically, the reduction of LH levels can beuseful to treat endometriosis. In addition, the patient can be a human.

The present invention also provides a kit. The kit includes a firstcontainer and a second container. The first container includes acomposition that includes the biodegradable thermoplastic polyester andthe biocompatible polar aprotic solvent. The second container includesleuprolide acetate. These ingredients, their properties, and preferredamounts are as disclosed above. Preferably, the first container is asyringe and the second container is a syringe. In addition, theleuprolide acetate is preferably lyophilized. The kit can preferablyinclude instructions. Preferably, the first container can be connectedto the second container. More preferably, the first container and thesecond container are each configured to be directly connected to eachother.

The present invention also provides a solid implant. The solid implantincludes a biocompatible thermoplastic polyester and leuprolide acetate.The biocompatible thermoplastic polyester is at least substantiallyinsoluble in aqueous medium or body fluid. The solid implant has a solidor gelatinous microporous matrix, wherein the matrix is a coresurrounded by a skin. The solid implant can further include abiocompatible organic solvent. The biocompatible organic solvent ispreferably miscible to dispersible in aqueous or body fluid. Inaddition, the biocompatible organic solvent preferably dissolves thethermoplastic polyester. The amount of biocompatible organic solvent, ifpresent, is preferably minor, such as from 0 wt. % to about 20 wt. % ofthe composition. In addition, the amount of biocompatible organicsolvent preferably decreases over time. The core preferably containspores of diameters from about 1 to about 1000 microns. The skinpreferably contains pores of smaller diameters than those of the corepores. In addition, the skin pores are preferably of a size such thatthe skin is functionally non-porous in comparison with the core.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates serum leuprolide levels in dogs after administeringATRIGEL®-6% w/w drug and Lupron® formulations.

FIG. 2 illustrates testosterone suppression in dogs with ATRIGEL® andLupron® 90 day formulations.

FIG. 3 illustrates serum leuprolide levels after ATRIGEL® and LUPRON® 90day formulations administration in dogs (n=8), dosed at 22.5 mg LA.

FIG. 4 illustrates serum testosterone levels after ATRIGEL® and LUPRON®90 day formulations administration in dogs (n=8), dosed at 22.5 mg LA.

FIG. 5 illustrates serum testosterone levels in rats—4 monthformulations, 14,860 daltons vs. 26,234 daltons.

DETAILED DESCRIPTION OF THE INVENTION

Specific and preferred biodegradable thermoplastic polyesters and polaraprotic solvents; ranges of thermoplastic polyesters, polar aproticsolvents, leuprolide acetate, and flowable compositions; molecularweights of the thermoplastic polyester; and ranges of the solid implantdescribed herein below are for illustration only; they do not excludeother biodegradable thermoplastic polyesters and polar aprotic solvents;ranges of thermoplastic polyesters, polar aprotic solvents, leuprolideacetate, and flowable compositions; molecular weights of thethermoplastic polyester; and ranges of the solid implant.

The present invention provides a flowable composition suitable for useas a controlled release implant, a method for forming the flowablecomposition, a method for using the flowable composition, thebiodegradable implant that is formed in situ from the flowablecomposition, a method of forming the biodegradable implant in situ, amethod for using the biodegradable implant that is formed in situ, a kitthat includes the flowable composition, and the solid implant. Theflowable composition may be used to provide a biodegradable orbioerodible microporous in situ formed implant in animals. The flowablecomposition is composed of a biodegradable thermoplastic polymer orcopolymer in combination with a suitable polar aprotic solvent. Thebiodegradable thermoplastic polyesters or copolymers are substantiallyinsoluble in water and body fluid, biocompatible, and biodegradableand/or bioerodible within the body of an animal. The flowablecomposition is administered as a liquid or gel to tissue wherein theimplant is formed in situ. The composition is biocompatible and thepolymer matrix does not cause substantial tissue irritation or necrosisat the implant site. The implant can be used to deliver leuprolideacetate.

Preferably, the flowable composition can be a liquid or a gel, suitablefor injection in a patient (e.g., human). As used herein, “flowable”refers to the ability of the composition to be injected through a medium(e.g., syringe) into the body of a patient. For example, the compositioncan be injected, with the use of a syringe, beneath the skin of apatient. The ability of the composition to be injected into a patientwill typically depend upon the viscosity of the composition. Thecomposition will therefore have a suitable viscosity, such that thecomposition can be forced through the medium (e.g., syringe) into thebody of a patient. As used herein, a “liquid” is a substance thatundergoes continuous deformation under a shearing stress. ConciseChemical and Technical Dictionary, 4th Enlarged Ed., Chemical PublishingCo., Inc., p. 707, NY, N.Y. (1986). As used herein, a “gel” is asubstance having a gelatinous, jelly-like, or colloidal properties.Concise Chemical and Technical Dictionary, 4th Enlarged Ed., ChemicalPublishing Co., Inc., p. 567, NY, N.Y. (1986).

Biodegradable Thermoplastic Polyester

A thermoplastic composition is provided in which a solid, biodegradablepolyester and leuprolide acetate are dissolved in a biocompatible polaraprotic solvent to form a flowable composition, which can then beadministered via a syringe and needle. Any suitable biodegradablethermoplastic polyester can be employed, provided the biodegradablethermoplastic polyester is at least substantially insoluble in aqueousmedium or body fluid. Suitable biodegradable thermoplastic polyestersare disclosed, e.g., in U.S. Pat. Nos. 5,324,519; 4,938,763; 5,702,716;5,744,153; and 5,990,194; wherein the suitable biodegradablethermoplastic polyester is disclosed as a thermoplastic polymer.Examples of suitable biodegradable thermoplastic polyesters includepolylactides, polyglycolides, polycaprolactones, copolymers thereof,terpolymers thereof, and any combinations thereof. Preferably, thesuitable biodegradable thermoplastic polyester is a polylactide, apolyglycolide, a copolymer thereof, a terpolymer thereof, or acombination thereof.

The type, molecular weight, and amount of biodegradable thermoplasticpolyester present in the composition will typically depend upon thedesired properties of the controlled release implant. For example, thetype, molecular weight, and amount of biodegradable thermoplasticpolyester can influence the length of time in which the leuprolideacetate is released from the controlled release implant. Specifically,in one embodiment of the present invention, the composition can be usedto formulate a one month delivery system of leuprolide acetate. In suchan embodiment, the biodegradable thermoplastic polyester can preferablybe 50/50 poly (DL-lactide-co-glycolide) having a carboxy terminal group;can be present in about 30 wt. % to about 40 wt. % of the composition;and can have an average molecular weight of about 23,000 to about45,000. Alternatively, in another embodiment of the present invention,the composition can be used to formulate a three month delivery systemof leuprolide acetate. In such an embodiment, the biodegradablethermoplastic polyester can preferably be 75/25 poly(DL-lactide-co-glycolide) without a carboxy terminal group; can bepresent in about 40 wt. % to about 50 wt. % of the composition; and canhave an average molecular weight of about 15,000 to about 24,000.

The terminal groups of the poly(DL-lactide-co-glycolide) can either behydroxyl, carboxyl, or ester depending upon the method ofpolymerization. Polycondensation of lactic or glycolic acid will providea polymer with terminal hydroxyl and carboxyl groups. Ring-openingpolymerization of the cyclic lactide or glycolide monomers with water,lactic acid, or glycolic acid will provide polymers with the sameterminal groups. However, ring-opening of the cyclic monomers with amonofunctional alcohol such as methanol, ethanol, or 1-dodecanol willprovide a polymer with one hydroxyl group and one ester terminal groups.Ring-opening polymerization of the cyclic monomers with a diol such as1,6-hexanediol or polyethylene glycol will provide a polymer with onlyhydroxyl terminal groups.

Thermoplastic Polyester Molecular Weight

The molecular weight of the polymer used in the present invention canaffect the rate of leuprolide acetate release as long as the flowablecomposition has been used as an intermediate. Under these conditions, asthe molecular weight of the polymer increases, the rate of leuprolideacetate release from the system decreases. This phenomenon can beadvantageously used in the formulation of systems for the controlledrelease of leuprolide acetate. For relatively quick release ofleuprolide acetate, low molecular weight polymers can be chosen toprovide the desired release rate. For release of a leuprolide acetateover a relatively long period of time, a higher polymer molecular weightcan be chosen. Accordingly, a polymer system can be produced with anoptimum polymer molecular weight range for the release of leuprolideacetate over a selected length of time.

The molecular weight of a polymer can be varied by any of a variety ofmethods. The choice of method is typically determined by the type ofpolymer composition. For example, if a thermoplastic polyester is usedthat is biodegradable by hydrolysis, the molecular weight can be variedby controlled hydrolysis, such as in a steam autoclave. Typically, thedegree of polymerization can be controlled, for example, by varying thenumber and type of reactive groups and the reaction times.

Polar Aprotic Solvent

Any suitable polar aprotic solvent can be employed, provided thesuitable polar aprotic solvent is miscible to dispersible in aqueousmedium or body fluid. Suitable polar aprotic solvents are disclosed,e.g., in Aldrich Handbook of Fine Chemicals and Laboratory Equipment,Milwaukee, Wis. (2000); U.S. Pat. Nos. 5,324,519; 4,938,763; 5,702,716;5,744,153; and 5,990,194. The suitable polar aprotic solvent should beable to diffuse into body fluid so that the flowable compositioncoagulates or solidifies. It is also preferred that the polar aproticsolvent for the biodegradable polymer be non-toxic and otherwisebiocompatible. The polar aprotic solvent is preferably biocompatible.Examples of suitable polar aprotic solvents include polar aproticsolvents having an amide group, an ester group, a carbonate group, aketone, an ether, a sulfonyl group, or a combination thereof.Preferably, the polar aprotic solvent can be N-methyl-2-pyrrolidone,2-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, propylenecarbonate, caprolactam, triacetin, or any combination thereof. Morepreferably, the polar aprotic solvent can be N-methyl-2-pyrrolidone.

The polar aprotic solvent can be present in any suitable amount,provided the polar aprotic solvent is miscible to dispersible in aqueousmedium or body fluid. The type and amount of biocompatible polar aproticsolvent present in the composition will typically depend upon thedesired properties of the controlled release implant. For example, thetype and amount of biocompatible polar aprotic solvent can influence thelength of time in which the leuprolide acetate is released from thecontrolled release implant. Specifically, in one embodiment of thepresent invention, the composition can be used to formulate a one monthdelivery system of leuprolide acetate. In such an embodiment, thebiocompatible polar aprotic solvent can preferably beN-methyl-2-pyrrolidone and can preferably present in about 60 wt. % toabout 70 wt. % of the composition. Alternatively, in another embodimentof the present invention, the composition can be used to formulate athree month delivery system of leuprolide acetate. In such anembodiment, the biocompatible polar aprotic solvent can preferably beN-methyl-2-pyrrolidone and can preferably present in about 50 wt % toabout 60 wt. % of the composition.

The solubility of the biodegradable thermoplastic polyesters in thevarious polar aprotic solvents will differ depending upon theircrystallinity, their hydrophilicity, hydrogen-bonding, and molecularweight. Thus, not all of the biodegradable thermoplastic polyesters willbe soluble in the same polar aprotic solvent, but each biodegradablethermoplastic polymer or copolymer should have its appropriate polaraprotic solvent. Lower molecular-weight polymers will normally dissolvemore readily in the solvents than high-molecular-weight polymers. As aresult, the concentration of a polymer dissolved in the various solventwill differ depending upon type of polymer and its molecular weight.Conversely, the higher molecular-weight polymers will normally tend tocoagulate or solidify faster than the very low-molecular-weightpolymers. Moreover the higher molecular-weight polymers will tend togive higher solution viscosities than the low-molecular-weightmaterials.

For example, low-molecular-weight polylactic acid formed by thecondensation of lactic acid will dissolve in N-methyl-2-pyrrolidone(NMP)to give a 73% by weight solution which still flows easily through a23-gauge syringe needle, whereas a higher molecular-weightpoly(DL-lactide) (DL-PLA) formed by the additional polymerization ofDL-lactide gives the same solution viscosity when dissolved in NMP atonly 50% by weight. The higher molecular-weight polymer solutioncoagulates immediately when placed into water. The low-molecular-weightpolymer solution, although more concentrated, tends to coagulate veryslowly when placed into water.

It has also been found that solutions containing very highconcentrations of high-molecular-weight polymers sometimes coagulate orsolidify slower than more dilute solutions. It is suspected that thehigh concentration of polymer impedes the diffusion of solvent fromwithin the polymer matrix and consequently prevents the permeation ofwater into the matrix where it can precipitate the polymer chains. Thus,there is an optimum concentration at which the solvent can diffuse outof the polymer solution and water penetrates within to coagulate thepolymer.

The leuprolide acetate is preferably lyophilized prior to use.Typically, the leuprolide acetate can be dissolved in an aqueoussolution, sterile filtered, and lyophilized in a syringe. Thepolymer/solvent solution can be filled into another syringe. The twosyringes can then be coupled together and the contents can be drawn backand forth between the two syringes until the polymer/solvent solutionand the leuprolide acetate are effectively mixed together, forming aflowable composition. The flowable composition can be drawn into onesyringe. The two syringes can then be disconnected. A needle can beinserted onto the syringe containing the flowable composition. Theflowable composition can then be injected through the needle into thebody. The flowable composition can be formulated and administered to apatient as described in, e.g., U.S. Pat. Nos. 5,324,519; 4,938,763;5,702,716; 5,744,153; and 5,990,194; or as described herein. Once inplace, the solvent dissipates, the remaining polymer solidifies, and asolid structure is formed. The solvent will dissipate and the polymerwill solidify and entrap or encase the leuprolide acetate within thesolid matrix.

The release of leuprolide acetate from these solid implants will followthe same general rules for release of a drug from a monolithic polymericdevice. The release of leuprolide acetate can be affected by the sizeand shape of the implant, the loading of leuprolide acetate within theimplant, the permeability factors involving the leuprolide acetate andthe particular polymer, and the degradation of the polymer. Dependingupon the amount of leuprolide acetate selected for delivery, the aboveparameters can be adjusted by one skilled in the art of drug delivery togive the desired rate and duration of release.

The amount of leuprolide acetate incorporated into the flowable,in-situ, solid forming implant depends upon the desired release profile,the concentration of leuprolide acetate required for a biologicaleffect, and the length of time that the leuprolide acetate has to bereleased for treatment. There is no critical upper limit on the amountof leuprolide acetate incorporated into the polymer solution except forthat of an acceptable solution or dispersion viscosity for injectionthrough a syringe needle.

The lower limit of leuprolide acetate incorporated into the deliverysystem is dependent simply upon the activity of the leuprolide acetateand the length of time needed for treatment. Specifically, in oneembodiment of the present invention, the composition can be used toformulate a one month delivery system of leuprolide acetate. In such anembodiment, the leuprolide acetate can preferably be present in about 2wt. % to about 4 wt. % of the composition. Alternatively, in anotherembodiment of the present invention, the composition can be used toformulate a three month delivery system of leuprolide acetate. In suchan embodiment, the leuprolide acetate can preferably be present in about4 wt. % to about 8 wt. % of the composition. The solid implant formedfrom the flowable system will release the leuprolide acetate containedwithin its matrix at a controlled rate until the leuprolide acetate iseffectively depleted.

Dosages

The amount of flowable composition administered will typically dependupon the desired properties of the controlled release implant. Forexample, the amount of flowable composition can influence the length oftime in which the leuprolide acetate is released from the controlledrelease implant. Specifically, in one embodiment of the presentinvention, the composition can be used to formulate a one month deliverysystem of leuprolide acetate. In such an embodiment, about 0.20 mL toabout 0.40 mL of the flowable composition can be administered.Alternatively, in another embodiment of the present invention, thecomposition can be used to formulate a three month delivery system ofleuprolide acetate. In such an embodiment, about 0.30 mL to about 0.50mL of the flowable composition can be administered.

Surprisingly, it has been discovered that the liquid polymericcompositions according to the present invention are more effective indelivering leuprolide acetate than Lupron® Depot. Specifically, as shownin the Examples below, the testosterone levels obtained with the liquidpolymeric compositions of the present invention containing theleuprolide acetate are lower at extended times in dogs compared toLupron® Depot, and also at the six month point in humans, compared tothe value reported in the literature for Lupron® Depot (Sharifi, R., J.Urology, Vol. 143, January, 68 (1990)).

All publications, patents, and patent documents are incorporated byreference herein, as though individually incorporated by reference. Theinvention will now be illustrated with the following non-limitingexamples.

Examples Example 1

Poly(DL-lactide-co-glycolide) having a 50/50 ratio of lactide toglycolide and a terminal carboxyl group (RG 504H from BoehringerIngelheim) was dissolved in N-methyl-2-pyrrolidone (NMP) to give a 34%by weight polymer solution. This ATRIGEL® polymer solution was filledinto 1.25 cc polypropylene syringes with a female luer lock fitting at avolume of 330 cL and terminally sterilized by exposure to gammairradiation at 20 kilograys. The molecular weight of the polymer aftergamma irradiation was 32,000 daltons. Leuprolide acetate was dissolvedin water, sterile filtered through a 0.2 cm filter, and filled into a1.00 cc polypropylene syringe with a male luer-lock fitting. The aqueoussolution was frozen and the water removed under vacuum to give a 10.2 mglyophilized cake of the peptide. The two syringes were coupled justprior to use and the contents mixed back and forth between the twosyringes for 30 cycles. The formulation was drawn back into the syringewith the male coupling, the two syringes separated, and a one-half inch20 gauge needle was attached. The contents of the syringe were theninjected subcutaneously into 7 male beagle dogs to give a total of 250mg of polymer formulation containing 7.5 mg of leuprolide acetate.Lupron® Depot microspheres with 7.5 mg of leuprolide acetate wereinjected intramuscularly into a second set of 7 beagle dogs. Serumsamples were collected from all of the dogs at baseline and days 1, 3,7, 14, 21, 28, 35, 42, 49, 55, 63, 77, and 91.

The serum samples were analyzed for testosterone using an RIA method.The results given in Table 1 show that both products are effective inlowering the testosterone concentrations below the human castrate levelof 0.5 ng/mL after about 14 days, and maintaining this effect out to day42. Overall, it appeared that the testosterone levels obtained with theLupron® Depot were slightly lower than those observed with the ATRIGEL®polymer system.

TABLE 1 Serum Testosterone Data in Dogs Testosterone Levels, ng/mL Time,Days ATRIGEL ® Lupron ® 1 2.23 3.52 3 5.50 4.85 7 0.47 1.05 14 0.60 0.3921 0.36 0.07 28 0.24 0.08 35 0.15 0.07 42 0.51 0.31 49 2.09 0.30 55 2.851.08 63 4.95 0.77 77 4.82 1.22 91 2.23 2.84

Example 2

The same polymer solution as described in Example 1 was sterile filteredthrough a 0.2 cm filter to give a polymer formulation with a molecularweight of 48,000 daltons. The sterile polymer solution was then filledaseptically into the female polypropylene syringes. Also, the same bulkpolymer solution before sterile filtration was divided into fourdifferent samples, filled into polypropylene syringes and exposed togamma irradiation at four irradiation levels to degrade the polymer todifferent molecular weights. The polymer after irradiation at thedifferent dosage levels had molecular weights of 33,500, 26,500, 23,000,and 20,000 daltons. All five formulations were combined with leuprolideacetate as described above and injected subcutaneously into male beagledogs. Determination of serum testosterone over a 45-day period showedthat all of the formulations were effective in reducing the testosteroneconcentrations below castrate levels except for the formulation with thelowest molecular weight of 20,000 daltons. Thus, the ATRIGEL® polymerformulation containing leuprolide acetate is effective in reducingtestosterone for 1 month over a wide range of polymer molecular weightsranging from 23,000 to 45,000 daltons.

Example 3

The polymer formulation described in Example 1 after gamma irradiationat 20 kilograys was combined with leuprolide acetate and injectedsubcutaneously into 8 male beagle dogs. Lupron® Depot containing 7.5 mgof leuprolide acetate was injected intramuscularly into 8 male beagledogs. Samples of serum were collected at baseline and days 1, 2, 3, 7,14, 22, 28, 30, 32, 34, and 36. The serum samples were analyzed forserum testosterone and serum leuprolide by RIA. The values for the serumtestosterone concentrations given in Table 2 show that both productswere effective in dogs in reducing the testosterone to below humancastrate levels with the Lupron® Depot product appearing to be slightlymore effective at the later time points. It was thought that the reasonfor this difference was the higher serum leuprolide levels for theLupron® Depot product at the intermediate time points as shown in Table3. Based upon this data, it was anticipated that the ATRIGEL® productwith leuprolide would be effective, but perhaps not as efficacious asthe Lupron® Depot product.

TABLE 2 Serum Testosterone Data in Dogs Testosterone Levels, ng/mL Time,Days ATRIGEL ® Lupron ® 1 4.56 5.09 2 5.81 6.19 3 6.69 4.99 7 0.55 1.9014 0.66 0.24 22 0.96 0.15 28 0.49 0.11 30 1.01 0.17 32 0.90 0.25 34 1.530.35 36 0.98 0.27

TABLE 3 Serum Leuprolide Data in Dogs Serum Leuprolide Levels, ng/mLTime, Days ATRIGEL ® Lupron ® 1 3.98 1.94 2 2.34 1.41 3 0.81 0.93 7 1.011.55 14 0.29 1.99 22 0.58 2.11 28 0.47 0.70 30 0.68 0.49 32 0.51 0.31 340.41 0.53 36 0.25 0.18

Example 4

The polymer formulation described in Example 1 was prepared under GMPconditions, loaded into syringes, and irradiated at 20 kilograys. Thesterile polymer solution was then combined with leuprolide acetate whichhad been sterile filtered into another syringe. The two syringes werecoupled, the contents mixed together for 30 cycles, and the contentsinjected subcutaneously into prostate cancer patients who had beenorchiectomized. Samples of serum were collected over 28 days andanalyzed for leuprolide concentration using a validated RIA method. Thedata given in Table 4 show an initial burst of drug followed by fairlyconstant levels over 28 days. When these data are compared to those forLupron® Depot published in the literature, the values are quite similar,and it is expected that both products will provide the same efficacy inprostate cancer patients.

TABLE 4 Serum Leuprolide Data in Humans Serum Leuprolide Levels, ng/mLTime, Days ATRIGEL ® Lupron ®¹ 0.167 25.26 20 14 0.28 — 17 — 0.8 21 0.37— 28 0.42 0.36 ¹Sharifi

Example 5

The ATRIGEL® leuprolide product described in Example 4 was injectedsubcutaneously (s.c.) into prostate cancer patients in a pivotalclinical trial. Every 28 days, the patients were given another injectionof the product until 6 injections had been received. Samples of serumwere collected at various times and analyzed for testosteroneconcentration by a validated RIA method. The values given in Table 5show that the serum testosterone concentrations reached castrate valuesof 50 ng/dL (0.5 ng/mL) at 21 days. The testosterone concentrations thendeclined to 7.77 ng/dL at day 56 and remained at this level throughoutthe remainder of the study. A comparison of the testosteroneconcentrations to the published values obtained with Lupron® Depot asgiven in Table 5 shows the ATRIGEL® leuprolide product to be moreeffective as it produces a lower testosterone level in humans.

TABLE 5 Serum Testosterone Data in Humans Serum Testosterone Levels,ng/dL Time, Days ATRIGEL ®¹ Lupron ®² 0 397.8 370.6 4 523.0 552.7 2149.37 33.8 28 23.02 17.0 56 7.77 ≦15.0 84 7.77 ≦15.0 112 6.93 ≦15.0 1407.41 ≦15.0 168 7.58 ≦15.0 ¹= 36 patients ²= 56 patients (Sharifi)

Example 6

Poly(DL-lactide-co-glycolide) with a molar ratio of lactide to glycolideof 75/25 (Birmingham Polymer, Inc.) was dissolved in NMP to give asolution with 45% by weight polymer. This solution was filled into 3.0cc polyproylene syringes with a male luer lock fitting and terminallysterilized by exposure to gamma irradiation at 23.2-24.6 kilograys. Thepolymer molecular weight after irradiation was 15,094 daltons.Leuprolide acetate was dissolved in water, sterile filtered through a0.2 cm filter and filled into a polypropylene syringe with a male luerlock fitting. The aqueous solution was frozen and the water removed byvacuum to yield a lyophilized cake of leuprolide. The two syringes wereconnected together with a coupler immediately prior to use and thecontents of the two syringes mixed by moving the material back and forthbetween the two syringes for 40 cycles to provide a formulation with 6%by weight of leuprolide acetate. The product was then pulled into thesyringe with the male luer lock fitting and a one-half inch 20 gaugeneedle attached.

The formulation containing the leuprolide acetate was then injectedsubcutaneously into 5 male beagle dogs at a target dose of 25.6μg/kg/day. The commercially available 3-month Lupron® Depot microsphereswere injected intramuscularly into 5 male beagle dogs at the same targetdosage. The actual dosages were 31.4 μg/kg/day for the ATRIGEL®formulation with leuprolide and 25.3 μg/kg/day for the Lupron® Depotproduct. At baseline and on days 1,2, 3, 4, 7, 14, 21, 28, 35, 49, 63,71, 81, 91, 105, 120, 134, and 150, serum was collected from each of thedogs and analyzed for testosterone by RIA and for leuprolideconcentration by LC/MS/MS.

The data showed that the serum leuprolide levels were actually higherfor the ATRIGEL® formulation compared to the Lupron® Depot product overthe first 30 days, but then declined to the same levels as the Lupron®Depot product over the next 120 days (FIG. 1). However, the testosteronelevels were comparable for the two product during the 70 days, but thenthe Lupron® Depot product failed to maintain human castration levels oftestosterone. This result was surprising based upon the comparableleuprolide levels of the two products over the later time points.

Example 7

The same polymer formulation as described in Example 6 was prepared andfilled into 1.25 cc polypropylene syringes with a female luer lockfitting at a volume of 440 mL. The product was terminally sterilized byexposure to gamma irradiation at 23-25 kilograys. The molecular weightof the polymer after irradiation was 14,800 daltons. Leuprolide acetatewas dissolved in water, sterile filtered using a 0.2 cm filter, andfilled into a 1.00 cc polypropylene syringe with a male luer lockfitting. The aqueous solution was frozen and the water removed by vacuumto give a 28.2 mg lyophilized cake of leuprolide acetate. Immediatelybefore use, the two syringes were coupled together and the contentsmixed by moving the materials back and forth between the two syringesfor 40 cycles to provide a homogeneous mixture with 6% by weightleuprolide acetate. The formulation was then pulled into the syringewith the male luer lock fitting, the syringes disconnected, and aone-half inch 20 gauge needle attached.

The formulation was injected subcutaneously into 8 male beagle dogs togive a total delivered dose of 22.5 mg of leuprolide acetate. Thecommercially available 3-month Lupron® Depot microspheres were injectedintramuscularly into 8 male beagle dogs. At 6 and 12 hours, and on days1, 2, 3, 7, 14, 21, 28, 35, 49, 64, 77, and 91 serum samples werecollected for analysis of testosterone and leuprolide concentrations. Onday 91, the animals were injected again with the formulations and serumcollected at 6 and 12 hours on day 91 and again on days 92, 93, 94, 99,and 105. The mean serum leuprolide concentrations were much higher forthe Lupron® Depot product than the ATRIGEL® formulation at the extendedtime points as shown in Table 6 and FIG. 3. However, the testosteroneconcentrations were actually lower for the ATRIGEL® formulation as shownin Table 7 and FIG. 4.

TABLE 6 Mean (SD) Serum Leuprolide Levels (ng/ml) in Dogs (n = 8) afterATRIGEL ® and LUPRON ® 3-Month Administration Mean, LA Mean, LA Time,day (ATRIGEL) (Lupron) 0 0.1 0.1 0.25 221.38 21.5 0.5 54.13 5.99 1 24.294.43 2 9.01 3.43 3 6.23 1.61 7 1.25 1.08 14 0.99 1.16 21 0.35 4.16 280.31 1.24 35 0.27 1.73 49 0.45 1.04 64 0.34 1.78 77 0.29 1.59 91 0.170.78 91.25 254.88 25.15 91.5 84.74 6.85 92 17.61 4.63 93 7.32 4.36 945.27 4.11 99 2.04 2.48 105 0.85 1.35

TABLE 7 Mean (SD) Serum Testosterone Levels (ng/ml) in Dogs (n = 8)after ATRIGEL ® and LUPRON ® 3- Month Administration Mean T Mean T Time,day Baseline, T (ATRIGEL) (Lupron) 0 2.29 1.42 3.38 0.25 2.29 3.45 5.250.5 2.29 2.92 5.67 1 2.29 2.99 6.35 2 2.29 4.14 5.74 3 2.29 3.98 6.92 72.29 1.51 3.46 14 2.29 0.17 0.95 21 2.29 0.06 1.38 28 2.29 0.14 1.13 352.29 0.29 1.11 49 2.29 0.2 0.07 64 2.29 0.05 0.07 77 2.29 0.05 0.08 912.29 0.06 0.34 91.25 2.29 0.06 0.22 91.5 2.29 0.05 0.22 92 2.29 0.050.14 93 2.29 0.09 0.22 94 2.29 0.07 0.22 99 2.29 0.06 0.08 105 2.29 0.050.08

Example 8

Three polymer formulations containing 45% by weight of 75/25poly(DL-lactide-co-glycolide) having different molecular weights wereprepared and filled into 1.25 cc polypropylene syringes with female luerlock fittings at a volume of 440 mL. The syringes were terminallysterilized by exposure to gamma irradiation at 23-25 kilograys. Themolecular weights of the three polymers after irradiation were 11,901,13,308, and 21,268. These polymer solutions were combined withlyophilized leuprolide acetate in another syringe and injectedsubcutaneously in dogs at a dosage of 22.5 mg as described in Example 7.Serum samples were collected at baseline and days 1, 7, 14, 21, 28, 35,42, 56, 70, 84, 98, 112, and 126. The serum was analyzed fortestosterone concentration by RIA. The data showed that the two lowermolecular weight polymer formulations failed to suppress thetestosterone concentrations below castrate for the full 90 days whereasthe polymer with the molecular weight of 21,268 was effective over the 3months evaluated.

Example 9

Two polymer formulations containing 45% by weight 75/25poly(DL-lactide-co-glycolide) having different molecular weights wereprepared and filled into 1.25 cc polypropylene syringes. The syringeswere terminally sterilized by exposure to gamma irradiation at 24-27kilograys. The molecular weights of the two polymers after irradiationwere 14,864 and 26,234 daltons. These polymer solutions were combinedwith lyophilized leuprolide acetate in another 1.25 cc polypropylenesyringe and mixed back and forth for 40 cycles to produce a homogenousmixture with leuprolide acetate at 6% by weight. The contents were thenpulled into one syringe, the syringes disconnected, and a one-half inch20 gauge needle attached. The formulation with leuprolide acetate wasthen injected subcutaneously into 5 rats per group at a dosage of 100pg/kg/day (12 mg/kg). At baseline and on days 3, 7, 14, 21, 35, 49, 63,70, 80, 91, 105, 120, and 132 serum samples were collected from all ofthe animals and analyzed for testosterone concentration using an RIAmethod. The data shown in FIG. 5 indicate that both polymer molecularweight formulations were effective in suppressing testosterone below thehuman castrate level for 132 days.

1-46. (canceled)
 47. A flowable composition suitable for use as acontrolled release implant, the composition comprising: (a) abiodegradable thermoplastic copolymer of lactide and glycolide includinga diol residue, wherein the copolymer has a weight average molecularweight of about 15,000 to about 45,000; (b) N-methyl-2-pyrrolidone; and(c) leuprolide acetate in an amount sufficient to reduce LHRH levels ina human.
 48. The flowable composition of claim 47, wherein the diolresidue is included as a chain extender.
 49. The flowable composition ofclaim 47, wherein the diol is 1,6-hexanediol.
 50. A biodegradableimplant formed in situ, in a patient, by the steps comprising: (a)injecting the flowable composition of claim 47 within the body of thepatient; and (b) allowing the N-methyl-2-pyrrolidone to dissipate toproduce a solid, biodegradable implant.
 51. A method of reducing serumtestosterone levels in a human comprising injecting a flowablecomposition comprising: (a) a biodegradable thermoplastic copolymer oflactide and glycolide including a diol residue, wherein the copolymerhas a weight average molecular weight of about 15,000 to about 45,000;(b) N-methyl-2-pyrrolidone; and (c) leuprolide acetate in an amountsufficient to reduce LHRH levels in a human; wherein the flowablecomposition is injected within a body tissue of the human so that theN-methyl-2-pyrrolidone diffuses in the body fluid of the human to causeprecipitation of the copolymer of lactide and glycolide to form an insitu solid implant.